"if consuming is almost constant, how come, over capacity can toast the grid??"

I think the problem is consumption is not constant. You say there it said they had to ask people to reduce usage. Perhaps what they are trying to say is the incomming grid cannot handle the power produced from the Germans mills, they get to much incomming overloading that end of the system when demand is high. Maybe like you have 220V, it's 2 legs of 110V. So if you had a 100amp service and balance the load 50amps each leg no problem, but 100amps on one leg might fry faulty low end wires or something. So maybe the leg comming in from Germany sends in too much durring peaks and over loads that leg, which of course powers many places at once. It goes down and dumps the total load onto the remaing leg which then cannot handle the sudden dump and also goes down.

Or think of 2 gennies running to power a large load. Path of least resistance, the closest gennie supplies the largest part of a close load and the extra load is supplied by a further away gennie. All is fine, now take out a 50 amp gennie and put in a 150 amp gennie with the same wires, breakers etc... The loads try to draw off the larger closer gennie more than the furthest genie but the old wire and circuits for the small 50amp gennie can't handle the load from the 150 amp gennie.

Just one type thought/idea.
Hope I actaully said that close to what I was thinking here so it makes some kind of sence :)
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nothing to lose

It's a bit clearer now, this minister who was talking in this article was just blaming windmills, I think to get a better understanding to the people that new extra power lines must be build. People in Holland just don't want more power lines, every ware you look power lines is what you see. Germany really needs to take care of there own grid.